According to IMDB, Watchmen's Screenplay was written by David Hayter and Alex Tse, and this silly joke was lifted directly from that.
Hayter's other writing credits include the X-Men movies and the Scorpion King, Tse's other writing credits include lots of anime... take that for what it's worth.
Like I said before; I never saw the Watchmen Movie but I read the comic and it seems pretty close based on what is displayed here, I think it got critical aclaim too... but I digress.
It's a joke everyone, really!